You really can learn a lot from this drill. Again, it is a simple thing and what is better it is free. You don’t need expensive cameras to find out if you are moving your head or swaying, two very important fundamentals. If you can learn to keep your head steady and centered over the ball on the ground, you will also learn to keep a solid left side, to “post up” so to speak on your left side, and to release the club head through impact down the target line. The key to turning your shoulders is to turn your hips through the ball, this enables you to clear your left side, keep the club on plane, and get the ball going toward your target.